1. Field of the Invention
Embodiments of the present invention generally relate to disaster recovery of a computer system and, more particularly, to a method and system for rapid failback of a computer system in a disaster recovery environment.
2. Description of Related Art
Computer systems having disaster recovery capabilities are desirable for many workplace environments. Such systems are intended to rapidly transfer computing functions from a failed computer (primary computer) to a secondary computer with minimal impact on a user. Once the failed computer returns to operation, the disaster recovery is completed by returning the computing functions to the primary computer.
Businesses and organizations depend upon the data stored on these systems and expect that, after a disaster, the recovery process will be quick. In the event of a computer virus, data corruption, system failure, power outage, or any natural disaster, without a system for disaster recovery, data may be lost or become inaccessible for a period of time while the disaster recovery process is occurring. Therefore, to protect system data and facilitate rapid disaster recovery, the data is replicated from one computer system to a remote computer system. The replicated data is available to a user upon failover of the primary computer to the secondary computer. A disaster recovery operation has two components: failover, where the secondary computer operates as the primary computer when the primary computer fails, and failback, where the computing function assumed by the secondary computer is returned to the primary computer upon the primary computer becoming functional.
More specifically, to prepare for a failover, data is backed up (replicated) from a primary computer to a secondary computer. The secondary computer is typically remote to the primary computer and stores a duplicate image of a primary data storage as a secondary data storage. The secondary data storage is used for disaster recovery, i.e., restoring the primary data storage in the event of a failure of the primary computer. Upon failover, the secondary computer assumes the role of the primary computer and writes data to the secondary data storage.
Recovery and restoration of data should occur as quickly and seamlessly as possible. The restored primary computer needs to resume the computing functions of application software as rapidly as possible. During a conventional failback operation, applications cannot be restarted on the primary computer until the secondary data storage is synchronized with the primary data storage, i.e., all of the data written to the secondary data storage after failover is copied to the primary data storage. The recovery operation may take a prolonged period of time, depending on the amount of data that needs to be copied from the secondary data storage to the primary data storage.
Businesses require failover and failback operations to occur as rapidly and as seamlessly as possible. More importantly, prompt access to all of the data, i.e. data written by the primary computer prior to failover and data written by the secondary computer after failover, is desirable. Conventional failback does not allow access to all of the data until synchronization between the primary data storage and the secondary data storage is complete.
Thus, there is a need in the art for a method and system of rapidly performing a failback operation of a computer system in a manner that provides access to all of the data prior to the completion of the synchronization operation.